Solid polymeric surfacing has a variety of uses, including household, commercial, and industrial uses in which durable, sometimes renewable, decorative surfaces are desired. Such surfaces include, but are not limited to, kitchen and other countertops, table tops, bathroom vanities, divider panels, and wall surfacing. These surfacing products may be produced so as to simulate stone such as marble or granite.
For example, U.S. Pat. Nos. 4,433,070, and 4,446,177 disclose compositions for such products. Additionally, U.S. Pat. Nos. 4,085,246 by Buser et al, 5,244,941 by Bruckbauer et al, and 5,242,968 by Minghetti et al, all of which are hereby incorporated by reference herein, disclose such compositions. U.S. Pat. No. 5,244,941 discloses a composition that is particularly useful as artificial stone surfacing, due to the inclusion of chips of a previously cured thermosetting resinous compound in the composition; also disclosed therein is the process for producing the surfacing. These products are typically produced in solid slabs about 1/2 inch in thickness. The result is surfacing of high quality, but relatively high cost.
It has been found previously that production and provision of these products in sheets about 1/8 inch in thickness results in a type of solid surfacing "veneer" having benefits similar to those of the 1/2 inch product, but at a significant reduction in cost. The 1/8 sheets are typically bonded to inexpensive particle board, or the like, resulting in a relatively strong but less expensive surfacing product.
The only method of producing 1/8 surfacing known to the prior art is with equipment that is prohibitively large and prohibitively expensive. Examples of such equipment are disclosed in U.S. Pat. Nos. 3,371,383 and 3,376,371. These references disclose a dual belt continuous casting system. This very expensive, very large, dual belt system is the only system that provides the degree of dimensional control necessary to produce a 1/8 thick sheet within required specifications and tolerances. The 1/2 inch product is produced on a similar single or dual belt system.
Problems with this prior art method of producing 1/8 sheets of surfacing also include the fact that the aesthetic results of the surfacing are limited when an artificial stone appearance is desired. As disclosed in U.S. Pat. No. 5,244,941, solid particulate is added to a resin matrix to give the surfacing a simulated stone appearance. Particulate is typically irregular in shape, but most approaches a quasi-spheroidal shape, and may be discussed as such for purposes herein. Naturally, the size of the particulate added to the resin matrix during the casting process is limited to the final thickness of the slabs; i.e, cast 1/8 inch thick surfacing cannot contain particulate that does not fit within the thickness of the sheet. This prohibits production of 1/8 inch thick product containing large sized particles that would result in a "chunky" look that occurs in some natural stone. This "chunky" look has been determined to be very aesthetically pleasing to consumers.
Lamellar, or disk-shaped, particles may be used, but with unacceptable results. Such particle shapes could have a maximum dimension that is greater than the sheet thickness and still fit within the sheet. However, the resin matrix typically is somewhat transparent, and the resultant effect from using lamellar shaped particles would not resemble the desirable "chunky" stone appearance. Instead the result would be oval and oblong particles that may partially disappear into the thickness of the sheet. Also, they may have a tendency to align during the sheet casting process, resulting in a less than random distribution of particles in the sheet.
Indeed, the only method of producing surfacing with a "chunky" look to date is by sanding or grinding relatively thick surfacing down in thickness to expose the interior (and thereby, a larger degree of flattened exposed surface area) of the particulate. This is necessary to produce a sheet with a surface look that is truly representative of the random nature of the particulate as dispersed in the resin matrix. As cast, the surface look of the slabs is not representative. Only the outer edges of the particulate approach the surface of the slab, and even then in only a tangential fashion. The random particulate pattern is not exposed until the sheet surface is sanded down. Indeed, some in the art feel that the sheet surfaces must be sanded down by 1/4 to 1/2 the diameter of the largest particulate size in the sheet to get the best aesthetic results. As one can plainly see, sheets are produced by this method at the expense of grinding off a huge amount of the material. Obviously, this method is very costly, in terms of the necessary manufacturing equipment, increased manufacturing time, and wasted surfacing material.
To produce relatively thin sheets of veneer, Applicants have attempted to slice 1/2 inch slabs of solid polymeric surfacing through their thickness using the type of saw that is typically used for cutting marble and granite. These attempts have been unsuccessful, in that the stone saws remove too much material during cutting and also produce a very rough, irregular surface that is unacceptable in solid surfacing veneer. These and other available saws that have been tried result in unacceptable levels of thickness variation within a sheet, unacceptable sheet curvature, unacceptable surface roughness and irregularity, an unacceptable decrease in sheet durability, and a high frequency of saw blade breakage. In fact, every industrial quality saw expert approached about developing a saw for such an application stated that it would be "impossible".
As a result, there exists a need to produce solid surfacing veneer, and in fact various thicknesses of solid surfacing, in a way that does not require the very large and expensive prior art equipment. There also exists a need for a method to produce simulated stone solid surfacing with an aesthetically pleasing "chunky" look, which cannot be accomplished by the prior art method. There also exists a need for apparatus that may be used to slice through the thickness of slabs of solid polymeric surfacing that overcomes the problems with prior art equipment.